[Federal Register Volume 72, Number 37 (Monday, February 26, 2007)]
[Proposed Rules]
[Pages 8311-8313]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-3169]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-27341; Directorate Identifier 2006-NM-272-AD]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model MD-11 and MD-
11F Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for all McDonnell Douglas Model MD-11 and MD-11F airplanes. This 
proposed AD would require installing bracket assemblies and jumper 
wires in the center main wheel well to improve the bonding path between 
the structure (wall) of the lower auxiliary fuel tank and its internal 
fuel pumps; measuring the electrical resistance between the fuel pump 
housings and the fuel tank structure; and doing corrective actions if 
necessary. This proposed AD results from fuel system reviews conducted 
by the manufacturer. We are proposing this AD to detect and correct an 
inadequate bond between the internal fuel pump housings and the 
structure of the lower auxiliary fuel tank. This condition, if not 
corrected, could fail to meet fault current requirements and result in 
a potential ignition source that, in combination with flammable fuel 
vapors, could cause a fuel tank explosion and consequent loss of the 
airplane.

[[Page 8312]]


DATES: We must receive comments on this proposed AD by April 12, 2007.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
    <bullet> DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
    <bullet> Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
    <bullet> Mail: Docket Management Facility, U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590.
    <bullet> Fax: (202) 493-2251.
    <bullet> Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    Contact Boeing Commercial Airplanes, Long Beach Division, 3855 
Lakewood Boulevard, Long Beach, California 90846, Attention: Data and 
Service Management, Dept. C1-L5A (D800-0024), for the service 
information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT: Samuel Lee, Aerospace Engineer, 
Propulsion Branch, ANM-140L, FAA, Los Angeles Aircraft Certification 
Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137; 
telephone (562) 627-5262; fax (562) 627-5210.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to submit any relevant written data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed in the ADDRESSES section. Include the docket number ``Docket No. 
FAA-2007-27341; Directorate Identifier 2006-NM-272-AD'' at the 
beginning of your comments. We specifically invite comments on the 
overall regulatory, economic, environmental, and energy aspects of the 
proposed AD. We will consider all comments received by the closing date 
and may amend the proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this proposed AD. Using the search function of 
that Web site, anyone can find and read the comments in any of our 
dockets, including the name of the individual who sent the comment (or 
signed the comment on behalf of an association, business, labor union, 
etc.). You may review DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or you 
may visit http://dms.dot.gov.

Examining the Docket

    You may examine the AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility office 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The Docket Management Facility office (telephone (800) 647-
5227) is located on the plaza level of the Nassif Building at the DOT 
street address stated in the ADDRESSES section. Comments will be 
available in the AD docket shortly after the Docket Management System 
receives them.

Discussion

    The FAA has examined the underlying safety issues involved in fuel 
tank explosions on several large transport airplanes, including the 
adequacy of existing regulations, the service history of airplanes 
subject to those regulations, and existing maintenance practices for 
fuel tank systems. As a result of those findings, we issued a 
regulation titled ``Transport Airplane Fuel Tank System Design Review, 
Flammability Reduction and Maintenance and Inspection Requirements'' 
(66 FR 23086, May 7, 2001). In addition to new airworthiness standards 
for transport airplanes and new maintenance requirements, this rule 
included Special Federal Aviation Regulation No. 88 (``SFAR 88,'' 
Amendment 21-78, and subsequent Amendments 21-82 and 21-83).
    Among other actions, SFAR 88 requires certain type design (i.e., 
type certificate (TC) and supplemental type certificate (STC)) holders 
to substantiate that their fuel tank systems can prevent ignition 
sources in the fuel tanks. This requirement applies to type design 
holders for large turbine-powered transport airplanes and for 
subsequent modifications to those airplanes. It requires them to 
perform design reviews and to develop design changes and maintenance 
procedures if their designs do not meet the new fuel tank safety 
standards. As explained in the preamble to the rule, we intended to 
adopt airworthiness directives to mandate any changes found necessary 
to address unsafe conditions identified as a result of these reviews.
    In evaluating these design reviews, we have established four 
criteria intended to define the unsafe conditions associated with fuel 
tank systems that require corrective actions. The percentage of 
operating time during which fuel tanks are exposed to flammable 
conditions is one of these criteria. The other three criteria address 
the failure types under evaluation: single failures, single failures in 
combination with a latent condition(s), and in-service failure 
experience. For all four criteria, the evaluations included 
consideration of previous actions taken that may mitigate the need for 
further action.
    We have determined that the actions identified in this AD are 
necessary to reduce the potential of ignition sources inside fuel 
tanks, which, in combination with flammable fuel vapors, could result 
in fuel tank explosions and consequent loss of the airplane.
    We have received a report indicating that the electrical bond may 
not be adequate between the internal fuel pumps of the lower auxiliary 
fuel tank and the fuel tank structure (wall), on Model MD-11 and MD-11F 
airplanes. This condition, if not corrected, could fail to meet fault 
current requirements and result in a potential ignition source that, in 
combination with flammable fuel vapors, could cause a fuel tank 
explosion and consequent loss of the airplane.

Related Rulemaking

    Operators should note that the same unsafe condition exists in 
certain McDonnell Douglas Model DC-10 airplanes and that we may issue a 
separate rulemaking to address those airplanes.

Relevant Service Information

    We have reviewed Boeing Service Bulletin MD11-28-127, dated 
September 19, 2006. The service bulletin describes procedures for 
installing bracket assemblies and jumper wires between the lower 
auxiliary fuel tank and its internal fuel pumps; for doing an 
electrical resistance measurement between the fuel pump housings and 
the auxiliary fuel tank wall; and for doing corrective actions if 
necessary. Corrective actions, if any resistance measurement exceeds 
2.5 milliohms, include reworking the electrical bonding between the 
fuel pump housings and the fuel tank wall. Accomplishing the actions 
specified in the service information is intended to adequately address 
the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to exist or

[[Page 8313]]

develop on other airplanes of this same type design. For this reason, 
we are proposing this AD, which would require accomplishing the actions 
specified in the service information described previously.

Costs of Compliance

    There are about 195 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 107 airplanes of 
U.S. registry. The following table provides the estimated costs for 
U.S. operators to comply with this proposed AD, at an average labor 
rate of $80 per work hour.

                                                 Estimated Costs
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                                                Work                                     Cost per
                   Action                      hours                Parts                airplane    Fleet cost
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Install bracket assemblies and jumper wires.        4  $1,928.........................      $2,248      $240,536
Do electrical resistance measurement........        1  None required..................          80         8,560
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Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, Section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would not 
have a substantial direct effect on the States, on the relationship 
between the national Government and the States, or on the distribution 
of power and responsibilities among the various levels of government.
    For the reasons discussed above, I certify that the proposed 
regulation:
    1. Is not a ``significant regulatory action'' under Executive Order 
12866;
    2. Is not a ``significant rule'' under the DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979); and
    3. Will not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD and placed it in the AD docket. See the 
ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec.  39.13  [Amended]

    2. The Federal Aviation Administration (FAA) amends Sec.  39.13 by 
adding the following new airworthiness directive (AD):

McDonnell Douglas: Docket No. FAA-2007-27341; Directorate Identifier 
2006-NM-272-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by April 12, 
2007.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to all McDonnell Douglas Model MD-11 and MD-
11F airplanes; certificated in any category.

Unsafe Condition

    (d) This AD results from fuel system reviews conducted by the 
manufacturer. We are issuing this AD to detect and correct an 
inadequate bond between the internal fuel pump housings and the 
structure (wall) of the lower auxiliary fuel tank. This condition, 
if not corrected, could fail to meet fault current requirements and 
result in a potential ignition source that, in combination with 
flammable fuel vapors, could cause a fuel tank explosion and 
consequent loss of the airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Installation of Brackets and Jumpers, and Resistance Measurement

    (f) Within 60 months after the effective date of this AD, do the 
actions described in paragraphs (f)(1) and (f)(2) of this AD, in 
accordance with the Accomplishment Instructions of Boeing Service 
Bulletin MD11-28-127, dated September 19, 2006.
    (1) Install bracket assemblies and jumper wires between the 
structure of the lower auxiliary fuel tank and its internal fuel 
pumps.
    (2) Do an electrical resistance measurement between the fuel 
pump housings and the lower auxiliary fuel tank wall.

Corrective Action

    (g) If any resistance measurement done in accordance with 
paragraph (f)(2) of this AD is greater than 2.5 milliohms on either 
fuel pump housing: Before further flight, rework the electrical 
bonding between the fuel pump housings and the lower auxiliary fuel 
tank wall as needed to achieve a resistance measurement of 2.5 
milliohms or less on both fuel pump housings, as described in Boeing 
Service Bulletin MD11-28-127, dated September 19, 2006.

Alternative Methods of Compliance (AMOCs)

    (h)(1) The Manager, Los Angeles Aircraft Certification Office 
(ACO), FAA, has the authority to approve AMOCs for this AD, if 
requested in accordance with the procedures found in 14 CFR 39.19.
    (2) Before using any AMOC approved in accordance with Sec.  
39.19 on any airplane to which the AMOC applies, notify the 
appropriate principal inspector in the FAA Flight Standards 
Certificate Holding District Office.

    Issued in Renton, Washington, on February 16, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E7-3169 Filed 2-23-07; 8:45 am]
BILLING CODE 4910-13-P